Conventionally, a backhoe equipped with an excavation working device is provided with hydraulic cylinders for rotating a boom, an arm, a bucket and another part, respectively. To rotate the boom, for example, a hydraulic cylinder is interposed between an intermediate portion of the boom and a boom bracket. However, the bucket drawn towards an operator causes soil or other foreign matter to stick to a rod of the hydraulic cylinder, so that, when the hydraulic cylinder is subsequently telescoped, the foreign matter damages a seal interposed in the hydraulic cylinder between a cylinder tube and the rod so as to cause problems such as oil leak. Therefore, a cover is provided on a front side of the piston rod of the hydraulic cylinder slidably in the longitudinal direction of the piston rod.
This cover for protecting the rod of the boom cylinder is sectionally V-like sloped so that, when a breaker (or the like) replacing the bucket is rotated to be drawn toward an operator and its tip touches the cover, the tip can easily escape sidewise along the slope of the cover. An example of the cover is disclosed in JP 2002-220853A.
With respect to a bucket cylinder for rotating the bucket, during excavation, the bucket cylinder is disposed on a foremost side so as to easily touch an obstacle. Therefore, a sectionally U-like shaped cover (as disclosed in JP H10-292426A) or a half-pipe-shaped cover (as disclosed in JP 2001-82414A) is provided so as to wholly cover the piston rod of the bucket cylinder from opposite sides.